Zhang Huiyu, Rong Shaopeng, Zhang Pengyi
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
ACS Appl Mater Interfaces. 2021 Apr 28;13(16):18944-18953. doi: 10.1021/acsami.1c05009. Epub 2021 Apr 16.
Solar light-induced catalysis has recently received great interest in efficiently and economically degrading volatile organic compounds, which deteriorate indoor and outdoor air quality. However, a few studies explored its essential photophysical and photochemical processes. Herein, the femtosecond transient absorption spectroscopy was used to investigate the decay of photogenerated holes in MnO with different Mn vacancies. About 67-93% of photogenerated holes recombined within a very short time (<130 ps), resulting in enhanced thermal catalytic activity of MnO. Besides, really a small portion of photogenerated holes remained unchanged in the detection time period (1400 ps). ESR tests further confirm that photocatalytic pathway plays a significant role in degrading VOCs besides the thermal catalytic pathway when MnO is under illumination of UV-visible light. The introduction of an appropriate content of Mn vacancy did prolong the lifetime of photogenerated carriers. This work clarifies the mechanism of photoirradiation in improving the catalytic activity of MnO and the effect of manganese defects on the catalytic reaction.
太阳光诱导催化最近在高效且经济地降解挥发性有机化合物方面引起了极大关注，这些挥发性有机化合物会恶化室内和室外空气质量。然而，仅有少数研究探索了其基本的光物理和光化学过程。在此，利用飞秒瞬态吸收光谱研究了具有不同锰空位的MnO中光生空穴的衰减。约67 - 93%的光生空穴在极短时间内（<130 ps）复合，导致MnO的热催化活性增强。此外，在检测时间段（1400 ps）内，确实有一小部分光生空穴保持不变。电子自旋共振测试进一步证实，当MnO在紫外 - 可见光照射下时，除了热催化途径外，光催化途径在降解挥发性有机化合物中也起着重要作用。引入适当含量的锰空位确实延长了光生载流子的寿命。这项工作阐明了光辐照提高MnO催化活性的机制以及锰缺陷对催化反应的影响。
